User interface for acquisition, display and analysis of ophthalmic diagnostic data

ABSTRACT

Improvements to user interfaces for ophthalmic imaging systems, in particular Optical Coherence Tomography (OCT) systems are described to improve how diagnostic data are displayed, analyzed and presented to the user. The improvements include user customization of display and reports, protocol driven work flow, bookmarking of particular B-scans, accessing information from a reference library, customized normative databases, and ordering of follow-up scans directly from a review screen. A further aspect is the ability to optimize the contrast and quality of displayed B-scans using a single control parameter. Virtual real time z-tracking is described that maintains displayed data in the same depth location regardless of motion.

PRIORITY

The present application is a continuation of U.S. patent applicationSer. No. 14/199,874, filed Mar. 6, 2014, which claims priority to U.S.Provisional Application Serial Number 61/785,347 filed Mar. 14, 2013,the contents of which are hereby incorporated in its entirety byreference.

TECHNICAL FIELD

The present invention relates to ophthalmic diagnostic testing andimaging, and in particular to graphical user interface improvements foracquisition, display and analysis of ophthalmic diagnostic data.

BACKGROUND

The field of ophthalmic diagnostics includes both imaging based orstructural techniques and functional approaches to diagnose and monitorvarious pathologies in the eye. One pathology of interest is glaucoma,an optic neuropathy resulting in characteristic visual field defects. Itarises from progressive damage to the optic nerve (ON) and retinalganglion cells (RGCs) and their axons, the retinal nerve fiber layer(RNFL). Investigating the relationship between development of functionaldamage in the visual field and structural glaucomatous changes of theRNFL has been the purpose of numerous studies [1-5].

Diagnostic instruments providing quantitative analyses in glaucomaassess either structural or functional aspects of the disease. OpticalCoherence Tomography (OCT) is one technique capable of imaging theretina and providing quantitative analysis of RNFL measurements andmeasuring the optic nerve head. OCT is a noninvasive interferometrictechnique that provides cross sectional images and thicknessmeasurements of various retinal layers including the RNFL (RNFLT) withhigh resolution [6] and good reproducibility [7-9]. Standard Automatedwhite-on-white Perimetry (SAP) is the standard for assessing visualfunction by examination of the visual field. Parametric tests are ableto provide quantitative measurements of differential light sensitivityat many test point locations in the visual field, and commerciallyavailable statistical analysis packages help clinicians in identifyingsignificant visual field loss [10]. The diagnostic performance of bothOCT and SAP in glaucoma as well as the correlation between SAP and OCTmeasurements has been investigated [11-14].

Clinical studies suggest that these diagnostic tests, used in isolation,provide useful information on the diagnosis and progression of thedisease and, used in conjunction, provide supportive and complementinginformation which could lead to improved accuracy in disease detectionand monitoring of progression. However, there is not one singlediagnostic test used in isolation that provides adequate diagnosticaccuracy and applicability across patient populations and diseasedynamic range. It is therefore desirable to collect, display and analyzedata from multiple ophthalmic diagnostic devices as is commerciallyavailable in the FORUM (Carl Zeiss Meditec, Inc. Dublin, Calif.)software package that allows customers to integrate and store ophthalmicdiagnostic data from and analysis from multiple modalities and performadditional analysis on the combined data. It may also be desirable todisplay data from multiple diagnostic modalities on a single instrumentso that the instrument operator can have the most complete picture ofthe patient for use in guiding the acquisition of data. Although thesituation has been described in detail for glaucoma, the need forinformation from multiple modalities, including structural andfunctional measurements, which may complement each other and aid indiagnosis and treatment management decisions when reviewed together, isgeneral to the ophthalmic field.

In commercially available ophthalmic diagnostic systems, the instrumentoperator typically selects from a series of scanning options based onknown locations in the eye that may be relevant to a specific pathology.The data is displayed and analyzed in standard formats specified by theinstrument manufacturer. As improvements in OCT technology allow forcollection of larger volumes of data without appreciable patient motionartifacts, there is more and more data to be analyzed and interpreted.It is desirable to increase automation and interpretation in the displayand analysis of these large volumes of data to improve and expandclinical applications of the technology.

SUMMARY

It is an object of the present invention to improve the ways in whichOCT and other ophthalmic diagnostic data is displayed, analyzed andpresented to the user. In one aspect of the present invention, the useris allowed to create customizable views or reports by dragging anddropping different display elements on the graphical user interface. Inanother aspect of the invention, the user is provided options to orderscans based on protocols for specific pathologies. Further enhancementsto the user interface include the ability to bookmark particularB-scans, access information from a reference library, and orderfollow-up scans directly from a review screen. A further aspect of thepresent invention is the ability to optimize the contrast and quality ofdisplayed B-scans using a single control parameter. In a further aspectof the invention, a virtual real time z-tracking approach is describedthat maintains displayed data in the same depth location regardless ofmotion. This embodiment may have specific application in the use of OCTin surgical systems. In a final aspect of the present invention, anophthalmic diagnostic instrument in which the user has the ability tocollect and perform analysis using a database of data on a normalpopulation that is of interest to them rather than the standardnormative database that is provided by the instrument manufacturer.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a generalized diagram of an ophthalmic OCT device that canbe used in various embodiments of the present invention.

FIGS. 2a and 2b show two examples of user customizable interface screensto drive acquisition, display and analysis of ophthalmic diagnostic dataaccording to an embodiment of the present invention. FIG. 2a shows adisplay for a Glaucoma Follow-up clinical view in which a variety ofdisplay elements relevant to glaucoma would be displayed and selected bya user to create a view of one or more sets of ophthalmic diagnosticdata. FIG. 2b shows a display when a new clinical view for Wet AMDfollow-up is selected. The user is given the option to select from apre-existing template of display elements or start from scratch.

FIGS. 3a and 3b show two examples of user customizable report screens todrive acquisition, display and analysis of ophthalmic diagnostic dataaccording to an embodiment of the present invention. FIG. 3a shows thework-up screen for Wet AMD in which various types of analysis can beselected by the user to generate a report on a particular patient. Theuser is able to select from existing data as well as indicating datathat should be acquired at a subsequent visit. FIG. 3b shows the reportgenerated based on the selections made from the display screen shown inFIG. 3a . Previously collected data is displayed while locations fordata pending acquisition are left blank.

FIG. 4a illustrates a user interface screen that could be used forprotocol driven workflows according to one aspect of the presentinvention. FIG. 4b displays the resulting data collected based on theworkflow request.

FIG. 5 shows a screen shot for an embodiment of the present invention inwhich particular B-scans for a cube of OCT data can be bookmarked forlater reference.

FIG. 6 shows a model of the eye that could be accessed from a referencelibrary during acquisition, display or analysis of ophthalmic diagnosticdata according to one aspect of the present invention.

FIG. 7a illustrates a review screen in which a fundus image is displayedalongside various OCT slices. FIG. 7b displays a high quality tomogramor B-scan that can be ordered directly from the review screen shown inFIG. 7a according to one aspect of the present invention.

FIG. 8 illustrates the basic concept behind virtual real time z-trackingin which a reduced subset of depth information is used to maintain aconstant depth view over time.

FIG. 9a shows an OCT B-scan in which 64 B-scans were registered andaveraged. FIG. 9b shows a contrast enhanced version of the image in FIG.9a according to one aspect of the present invention.

DETAILED DESCRIPTION

Optical Coherence Tomography (OCT) is a technique for performinghigh-resolution cross-sectional imaging that can provide images oftissue structure on the micron scale in situ and in real time [15]. OCTis a method of interferometry that determines the scattering profile ofa sample along the OCT beam. Each scattering profile is called an axialscan, or A-scan. Cross-sectional images (B-scans), and by extension 3Dvolumes, are built up from many A-scans, with the OCT beam moved to aset of transverse locations on the sample. OCT provides a mechanism formicrometer resolution measurements.

In frequency domain OCT (FD-OCT), the interferometric signal betweenlight from a reference and the back-scattered light from a sample pointis recorded in the frequency domain rather than the time domain. After awavelength calibration, a one-dimensional Fourier transform is taken toobtain an A-line spatial distribution of the object scatteringpotential. The spectral information discrimination in FD-OCT istypically accomplished by using a dispersive spectrometer in thedetection arm in the case of spectral-domain OCT (SD-OCT) or rapidlyscanning a swept laser source in the case of swept-source OCT (SS-OCT).

Evaluation of biological materials using OCT was first disclosed in theearly 1990's [16]. Frequency domain OCT techniques have been applied toliving samples [17]. The frequency domain techniques have significantadvantages in speed and signal-to-noise ratio as compared to time domainOCT [18]. The greater speed of modern OCT systems allows the acquisitionof larger data sets, including 3D volume images of human tissue. Thetechnology has found widespread use in ophthalmology. A generalizedFD-OCT system used to collect 3-D image data suitable for use with thepresent invention is illustrated in FIG. 1.

A FD-OCT system includes a light source, 101, typical sources includingbut not limited to broadband light sources with short temporal coherencelengths or swept laser sources [19-20]. Light from source 101 is routed,typically by optical fiber 105, to illuminate the sample 110, a typicalsample being tissues at the back of the human eye. The light is scanned,typically with a scanner 107 between the output of the fiber and thesample, so that the beam of light (dashed line 108) is scanned over thearea or volume to be imaged. Light scattered from the sample iscollected, typically into the same fiber 105 used to route the light forillumination. Reference light derived from the same source 101 travels aseparate path, in this case involving fiber 103 and retro-reflector 104.Those skilled in the art recognize that a transmissive reference pathcan also be used. Collected sample light is combined with referencelight, typically in a fiber coupler 102, to form light interference in adetector 120. The output from the detector is supplied to a processor130. The results can be stored in the processor or displayed on display140. The processing and storing functions may be localized within theOCT instrument or functions may be performed on an external processingunit to which the collected data is transferred. This unit could bededicated to data processing or perform other tasks which are quitegeneral and not dedicated to the OCT device.

The interference causes the intensity of the interfered light to varyacross the spectrum. The Fourier transform of the interference lightreveals the profile of scattering intensities at different path lengths,and therefore scattering as a function of depth (z-direction) in thesample [21]. The profile of scattering as a function of depth is calledan axial scan (A-scan). A set of A-scans measured at neighboringlocations in the sample produces a cross-sectional image (tomogram orB-scan) of the sample. A collection of B-scans collected at differenttransverse locations on the sample makes up a data volume or cube.

The sample and reference arms in the interferometer could consist ofbulk-optics, fiber-optics or hybrid bulk-optic systems and could havedifferent architectures such as Michelson, Mach-Zehnder or common-pathbased designs as would be known by those skilled in the art. Light beamas used herein should be interpreted as any carefully directed lightpath. In time-domain systems, the reference arm needs to have a tunableoptical delay to generate interference. Balanced detection systems aretypically used in TD-OCT and SS-OCT systems, while spectrometers areused at the detection port for SD-OCT systems. The invention describedherein could be applied to any type of OCT system. Various aspects ofthe invention could apply to other types of ophthalmic diagnosticsystems and/or multiple ophthalmic diagnostic systems including but notlimited to fundus imaging systems, visual field test devices, andscanning laser polarimeters. The invention relates to acquisitioncontrols, processing and display of ophthalmic diagnostic data that canbe done on a particular instrument itself or on a separate computer orworkstation to which collected diagnostic data is transferred eithermanually or over a networked connection. The display provides agraphical user interface for the instrument or operator to interact withthe system and resulting data. The instrument user can interact with theinterface and provide input in a variety of ways including but notlimited to, mouse clicks, touchscreen elements, scroll wheels, buttons,knobs, etc. Various aspects of a user interface design for OCTapplications have been described [22]. The invention described herein isdirected towards improvements in how the user interface is designed andconfigured to allow for optimized acquisition, display and analysis ofophthalmic diagnostic data.

Customizable User Interface and Reports

In one embodiment of the present invention, the user interface providesa fully customizable report/clinical view functionality. The user hasthe option to create their own clinical view template by dragging from alist of display elements or widgets as illustrated in FIG. 2a for apreferred embodiment for OCT imaging. FIG. 2a shows the screen thatwould be displayed when the Glaucoma follow up clinical view wasselected by the user by clicking or touching on the “Glaucoma Follow Up”button 201 in the top panel of the screen. Specific views for differentpathologies or disease states including but not limited to glaucoma andage related macular degeneration (AMD) may be created. Once a clinicalview is selected, the display will be populated by a collection ofdisplay elements or widgets. Widgets can be related to data display ordata analysis (comparison to normative data, measurements, progressionanalysis, from one or more instruments (OCT, Visual Field Testing,Fundus camera, etc.). In FIG. 2a , two of the displayed widgets are HFA202, and Progression 203. Furthermore, the user can add widgets to anexisting template “on the fly” by selecting from a list of categories(combo widgets, OCT, Fundus, HFA, etc.) that can be displayed somewhereon the screen. In a preferred embodiment of the invention, the userinterface displays the set of widgets available at a given time which donot require additional scan information; these widgets when selectedwill display data instantly. If the user selects widgets that requireadditional patient scan information, the user interface will generateand send orders to the acquisition controls of one or more instrumentsfor specific scans to be carried out in the future to collect therequested information. Data will be displayed when all the requiredscans are performed and saved on the patient record. Once a widget ordisplay element is selected, the user has the option to populate thewidget with different data. A list of available data and analysis 204can be displayed and the user can select from the list and indicatewhere in the widget the data should be displayed.

The user also has the option to create new views from scratch using thedelivered views as a template as illustrated in FIG. 2b for the Wet AMDclinical view. When the user selects “Add new view” 205 in FIG. 2a , theview shown in FIG. 2b could be displayed on the screen. The user isgiven the option to start with a predetermined template or start fromscratch 210. Once this selection is made, the view will change to thatshown in FIG. 2a where widgets relevant to the selected clinical viewwould be accessible via a list or menu somewhere on the screen. Thislist could be hidden when not in use to increase the available screenspace for display of clinically meaningful data. Data from multiplevisits can be displayed side by side to facilitate analysis of diseaseprogression as shown in the Analysis panel 211 in the bottom of FIG. 2b.

In a related embodiment of the present invention, the user has theoption to design one or more protocols/reports either from scratch or bychanging existing protocol/report templates in a similar manner to theuser interface as illustrated in FIG. 3. FIG. 3a shows a “Wet AMD workup” display in which the components that can be drawn from to generate areport relevant to wet AMD can be selected by the user. Various piecesof information about the identity of the patient 301 can be included inaddition to various types of ophthalmic imaging data. The user can onthe fly add to an existing report additional analysis, images or scans.The set of analysis, scans and images is limited to the existing scandata if immediate display of the data is desired. This is indicated bythe menu of “available” options 302 shown on the display. The user onlyhas to select and drag the analysis option or widget that they want toadd to the report from the list of available widgets on the bottom ofthe screen. The user can select from data collected at previous visitsusing a “history” display element on the screen where an indication ofearlier existing data sets would be provided. The user can also select awidget or dataset and choose to view all widgets or data of the sametype collected over all visits. Individual visits can be added orremoved to create the progression report desired. The user can alsoselect an analysis from which data is not presently available from themenu of “Requires additional analysis” options 304. In case, an analysisis requested that requires additional scan data, the system willautomatically generate a scan order and send it to the acquisition headof the diagnostic instrument. A report generated from a selection ofelements using the interface in FIG. 3a is shown in FIG. 3b . Data thathas been already collected is visible. The location on the report wherethis data is to be displayed will remain blank or labeled “ordered” 310until it is collected at a later date.

Protocol Driven Workflow

Typically for OCT imaging, a specific scan or series of scans will beselected by the instrument user and performed on the patient based ondesired information. This requires knowledge of what scan patterns arelikely to provide the desired information. An aspect of the presentinvention is the ability for the user to order single exams, or aparticular protocol which is a combination of one or more scans, oranalysis from a single or multiple different diagnostic devices. Thisprotocol driven workflow could be based on desired information on aspecific disease state such as glaucoma or dry or wet AMD. This workflowalso implies that the user can order the protocol for a particularpatient at the end of the examination for their next visit. Theinformation will be stored and recalled the next time the patient isexamined. The user can use existing protocol templates or generate theirown based on knowledge of desired information.

The user can order the next visit protocol/report during the currentvisit. The user only has to click on the order control at the bottom ofthe main screen and a pop-up screen will show-up as illustrated in FIG.4a . On this screen, the user can select which protocol to order fornext visit. Either the same as current visit, a new one (based onexisting templates), or order existing protocol and add additional scansto it. These orders will then be retrieving on 1 or more diagnosticacquisition devices. An example of a specific exam protocol isillustrated in FIG. 4a . Here a follow-up exam on dry AMD is desired anda pair of OCT scans as well as a fundus image is being ordered to allowfor follow-up examination of a patient. FIG. 4b shows some of the datathat is collected at the later visit based on the ordered examinationprotocol. If the user selects a new protocol, the system can determinethe scans that are required to create the full data set that would berequired by the standard scan presentation for that mode and create anorder for acquisition of those scans.

Bookmarking B-Scans

The user is provided with the capability to bookmark one or more scansin a cube of data after acquisition, during review at the acquisitionunit as is illustrated in FIG. 5. This function may be executed by thetechnician that is operating the instrument or by a doctor preparing ananalysis to share with the patient, or colleagues, or a referringclinician, or as a reminder for any future reviewer. The user willselect the scan that they want to highlight in the volume of data byscrolling up and down on the cube bar using any one of a number of userinput devices including but not limited to a touchscreen interface, ascroll wheel, a mouse, or one or more buttons to advance forward andbackward. After selecting the scan, the user will drag the bookmark iconto the scan using any user input means. This pre-screening step ofbookmarking B-scans will help highlight any type of pathology orabnormality that was noted during acquisition. In addition tobookmarking, the user can annotate a particular scan with notes ormeasurement information and this information will be stored with thedata for later recall.

Reference Library

In a further embodiment of the invention, the user interface allowsaccess to a reference library with educational material pertaining toeye anatomy, healthy reference scans and examples of diseased scans thatcan be accessed by the user throughout acquisition and analysis of theophthalmic diagnostic data as illustrated in FIG. 6. The user can clickon the library icon 601 on the bottom of the page to access the library.A scroll bar 602 can be the navigation tool on this screen. Afterselecting a particular scan/image the user can toggle from standard tofull screen. In addition, each of the scans/images has a control on theright upper corner to toggle between the patient scan and a healthreference scan for comparison. It is also possible for doctors to addtheir own information to the library. The model eye can be clicked on toselect a portion of the eye for which reference images are desired, suchas the fovea, the optic nerve head, the arcades, the angle, or thecornea.

Click to Scan

In the past, the operator has to identify the point(s) of interest on afundus view generated from either OCT data or a separate fundus imagingmodality during alignment and use that information to guide further dataacquisition. This can be challenging given the patients' motion andgiven the inherent differences in the visualization of structures in theOCT cross-sectional B-scan as compared to an en face fundus image whichmay be in color or contain functional information such as fluoresceinangiography. A further embodiment of the present invention allows theinstrument operator to identify the region of interest on a relativelymotion free fundus image in a review screen and to take a finer orhigher definition scan with patient's head still in position to bescanned. FIG. 7a illustrates a collection of data for a particularpatient. The data can include low definition B-scans 701 that can belinked via color coding to locations on a view of the patient's retinaor fundus 702. The fundus image could be generated from OCT data [23] orfrom an alternative imaging modality including but not limited to linescanning ophthalmoscope (LSO), fundus camera, confocal scanning laserophthalmoscope (cSLO). In addition a view of the patient's iris andpupil 703 can also be displayed to indicate where the OCT beam ispassing through the patient's eye.

During the acquisition of OCT data, after taking an overview scan of theeye, the operator reviews the overall scan and specifies a region ofinterest on the Fundus image 702 using any one of a variety of userinput devices including mouse clicks, touch screen, etc. The system canautomatically identify a region of interest such as the fovea or opticdisc or the user can adjust the line displayed on the fundus image toguide further data acquisition. The user can then click or select a highdefinition data scan using a user interface element on the display. Themachine acquires a finer scan at the region of interests with a higherresolution as illustrated in FIG. 7b . The increased resolution can beobtained by collecting multiple scans at the same location and averagingor by sampling at a higher density. Details of the location of the highdefinition scan 710 are displayed along with the data.

In a preferred embodiment of the present invention, during theacquisition of OCT data,

-   1. The operator takes an overview scan of patient's eye.-   2. While patients head is still in position for the next scan, the    operator reviews the overview scan.-   3. The operator specifies the region of interest guided by the    automatically identified landmark, such as fovea, by dragging the    mouse or a slice navigator.-   4. The instrument takes a scan with higher resolution than that of    the overview scan on the region of interest.

While the preferred embodiment involves selecting the region foradditional data collection while the patient's head is still positionedin the instrument, the same idea could be applied to review of data andordering of scans for subsequent visits. In addition, locations foradditional data collection could be selected from a preliminary cube ofOCT data such that any arbitrary location could be selected and scanscould be collected along any arbitrary axes or directions within thecube.

Method for Virtual Real-Time z-Tracking

In current OCT systems, as the tissue moves in the axial dimension, theposition of the tissue in the OCT signal could vary significantly. Henceit is desirable to have some form of z-tracking that tries to positionthe tissue in each B-Scan at the optimal location. However currentmethods rely on finding the position of the tissue and then moving areference mirror to adjust the position of the acquired data so that thetissue is positioned optimally. This is typically accomplished by amechanical movement of one of the arms of the interferometer. Howeverbecause of the mechanical movement (which is slow) the tissue mightnever be positioned optimally if there is constant motion and thealgorithms are constantly trying to catch up to the tissue. This isespecially undesirable if the user is taking some actions based on theOCT signal. For example, in an OCT system integrated with a surgicalmicroscope, the physician will be taking some actions based on thesignal they see on the display. Hence it is very desirable if the tissuecan be displayed at an optimal location (that can be set by the user) inreal-time. A further aspect of the present invention would enablereal-time z-tracked display of OCT data to the user. The invention willbe particularly useful for applications where it is very important tohave a stabilized “view” of the OCT data being acquired. One example isOCT for ophthalmic surgery.

The main idea of the present invention is to increase the OCT imagingdepth to a larger depth compared to the region of interest. Forinstance, if a surgeon is looking at the posterior region of the eye forsurgery, he is mainly interested in 2 to 4 mm of tissue. If a largerregion of tissue can be imaged, then automatic algorithms can be used tosegment the tissue region in the image in real-time. The displayedregion to the user can then be centered on the region of interest henceensuring that the tissue is always positioned at the optimal locationselected by the user. The main advantage of this method is that thecurrent invention can achieve z-tracked display in real-time.

With the development of new OCT technologies, especially swept sourceOCT, more imaging depth will become feasible. It has been shown thatimaging depths of 6 mm or more are possible with Swept Source systems.For the current discussion, we will use the example of an imaging depthof 6 mm and a region of interest of 3 mm (for imaging the posteriorsegment, this depth for the region of interest is usually sufficient).

FIG. 8 shows an overview of the concept. At time t1, the data isacquired as shown on the extreme left (Ex: 6 mm imaging depth).Automatic algorithms can segment the tissue of interest and a region ofinterest is placed around it as shown by lines 802 and 804 (Ex: 3 mm).This region of interest is displayed to the user as shown on the firstimage to the right of the arrow. At time t2, the tissue has moved alongthe axial dimension and hence is placed at a different location on theacquired data window as shown on the second image. The tissue can besegmented again and the region of interest moved to match the tissueregion of interest. The displayed image at time t2 has the tissue placedat the same location as in the displayed image at time t1. Since thesegmentation algorithm can be very fast, the display can be achieved inreal time and presents the user with a virtual real-time z-trackingcapability.

It should be noted that the depth of the region of interest is not alimitation. If the automatic algorithms determine that the tissue beingimaged is thicker than the currently set region of interest, then theregion of interest itself can be expanded to contain the tissue ofinterest. The only limitation will be the imaging depth that is possiblewith the instrument under consideration. If the tissue goes out of eventhe extended region of the scan, then traditional methods of moving thereference mirror might be needed to bring the tissue back into range.

The tissue region can be segmented from the OCT B-Scan using very fastthresholding algorithms. Since we are mainly interested in finding theregion of interest, the segmentation algorithms need not be precise. Arough segmentation of the tissue will be sufficient to center the regionof interest. Further, the data can be down-sampled as needed to increasethe speed of detection. Thresholding approaches are just one way toprovide segmentation. Additional ways to segment the data can beenvisioned by those skilled in the art.

Improved Contrast and Visual Quality of Averaged B-Scans Using a SingleControl Parameter

Typically, the user is provided with brightness and contrast (B,C)settings which they can vary to come up which an optimal setting fordisplay of a particular piece of OCT data. This is a two dimensionalexhaustive search within a pair of parameters that can vary within alarge range. A further aspect of the present invention provides the userwith just one parameter which varies between 0 and 1 to control thequality of the display, and hence is easy to understand, set, andinterpret.

After averaging a group of registered B-scans to improve Signal-to-Noise(SNR), the proposed method calculates a global, single value from thedata, and removes a fraction of it from the averaged data, resulting ina B-scan that shows significant improvements in intra-layer contrast,visibility of detail, and object-to-background contrast. The primaryapplication for this method is to improve the image quality of averagedB-scans. In alternative embodiment, it can be used to provide a reducedcontrol parameter set (n=1) to the user for setting the intensity levelof the image that provides better contrast. The parameter could bedisplayed and adjusted by the user without detailed knowledge of thespecific optimization process.

FIG. 9a shows the result of an averaging process, where a stack of 64frames, scanned at roughly the same anatomical location wereco-registered, and a median intensity value was obtained at each pixellocation. In a preferred embodiment of the proposed method, first a meanof these median values that make up the image at this stage iscalculated. Let us denote the median image by m, and the mean by <m>.The contrast enhancement is then obtained by subtracting a fraction ofthis <m>from m, for example according to:

m′ (improved)=m−(alpha)<m>.  (1)

An example of the improved image is shown in FIG. 9b , where theinterlayer contrast has increased, while still preserving the detailsfrom the vitreous to the outer extent of the choroid. The value ofalpha, that was subjectively determined to provide both a contrastenhancement and preservation of detail, is 0.58 in FIG.9 b. Also worthnoticing is that because of this modification induced in the originalimage by a single control parameter (equation 1 above), the visibilityof fine layers like the IS/OS boundary (arrows 901) is significantlyincreased.

User Generated Normative Databases

Current commercially available OCT systems such as Cirrus HD-OCT (CarlZeiss Meditec, Inc. Dublin, Calif.) provide the opportunity for doctorsto compare a particular patient to a collection of normative data foranalysis and disease diagnosis. Companies such as Carl Zeiss attempt toprovide a collection of data that will apply to a broad patientpopulation. In some cases, doctors want to compare their patients withtheir local normal population either because of ethnic variations orvariations due to specific disease conditions. Clinicians are typicallyimaging numerous patients for their own studies and want to use theirown patient population as the reference.

It is a further aspect of the present invention to enable users togenerate reference databases of their own, and to compare patients withthis reference databases. The deviation from the User GeneratedReference database can be visualized in the similar fashion of thedeviation from Normative Database. In a further embodiment, users canadjust the threshold of deviations to provide meaningful comparisonsdepending on the normative data. In addition, the user interface willallow doctors to export and import their customized reference databasesto allow for sharing between practitioners.

Although various applications and embodiments that incorporate theteachings of the present invention have been shown and described indetail herein, those skilled in the art can readily devise other variedembodiments that still incorporate these teachings.

The following references are hereby incorporated by reference:

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What is claimed is:
 1. A graphical user interface (GUI) for use withoptical coherence tomography (OCT) volume data, said interfacecomprising: a collection of display elements relating to display andanalysis of the OCT data, wherein the display elements can beselectively chosen and placed on the GUI in response to user input.